atomic radii of transition metals

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Question:Which of the following statements are CORRECT?
1.The atomic radii of transition metals decrease initially, then increase as one moves from left to right across a period of the periodic table.
2.The atomic radii of the period 6 transition metals are approximately 25% larger than the atomic radii of the period 5 transition metals.
3.The densities of the period 5 transition metals are greater than those from either the period 4 or period 6 transition metals.
a.1 only
b.2 only
c.3 only
d.1 and 2
e.1, 2, and 3

Answers:1 is true
2 is false
3 is false

Question:Which of the following are true about transition metal elements ?
(a) As the atomic number increases for d-block transition elements, electrons are added to outer s and p orbitals
(b) Metals in high oxidation states tend to be good oxidizing agents
(c) A common oxidation state of manganese is +4
(d) Going across a period the atomic radii does not change a great deal.
(e) As the atomic number increases for the lanthanides and actinides transition metal elements, electrons are added to an inner f orbital.

Answers:A is sometimes true, however they are generally added to the d orbitals. But when they form ions they generally try to form the most stable configuration which some times means losing electrons to another s orbital.
B is true, high positive charge means high attraction for electrons. So in a redox reaction it would probably be reduced making it the oxidizing agent
C is true
D is definitely not true. Sodium has an atomic radius of 180 pm which is larger than Uranium's which is 175 pm.
E is the same thing as A only with more possible orbitals.

Question:For eg, atomic radius decreases from left to right across a period. Yet Oxygen has a larger radius than Nitrogen.
I want to know all the other exceptions along with their reasons. Please help!
Thanks.

Answers:There are several definitions of atomic radius.
If you take the atomic radius as measured in covalent compounds there is an easily recognizable trend across a period (see link below) and Oxygen atoms are smaller than Nitrogen atoms.
Anomalous atomic radii occur in the transition metals as they fill intermediate orbitals and this gives rise to very different radii. Ionic radii in the transition metals are also heavily dependent on the charge on the ion - transition metals have various oxidation states and various ionic radii.

Question:hi, ive got 3 questions and would appreciate anyone answering...
1)how do the electron configurations of the different transition metals explain their location in the periodic table?
2) why do transition metals form complex compounds?
3)what property of transition metals makes some of them able to act as effective catalysts?
thanks to anyone who can help in advance... :) thanks gervald..., but how does the fact that they can have several oxidation states make them effective catalysts?

Answers:1) d electrons are the most important feature of the transition elements. They are placed in the groups with group numbers equal to that of nd + (n+1)s electrons. For example scandium has 1 3d electron and 2 4s electrons. So it falls in the Group 3 of the periodic table.
2)These complexes have variable valencies due to the change in the orbitals by electrons from s to d. They have ions that have a very large charge/mass ratios. So, the highly positive ions attract the ligands. These ligands donate their lone pairs to the atoms. These are placed in the d orbitals.
3) Variable valencies. The atoms of these elements act as electron acceptors first and then donate the electrons to the reactants. This bypass route drastically reduces the activation energy of the reaction and so we can use them as catalysts.

Chemistry: Transition metals and isomerism (2) :Chemistry: Transition metals and isomerism.Transition metal electron configurations for neutral atoms and cations. Coordination compounds; oxidation number and coordination number. Coordination isomers; linkage isomers. Structural isomers vs. stereoisomers. Geometric isomers. Optical isomers This is a recording of a tutoring session, posted with the students' permission. These videos are offered on a "pay-what-you-like" basis. You can pay for the use of the videos at my website: www.freelance-teacher.com For a list of all the available video series, arranged in suggested viewing order, go to my website. For a playlist containing all the videos in this series, click here: www.youtube.com (1) Transition metal electron configurations for neutral atoms and cations (2) Continued (3) Continued (4) Coordination compounds (5) Oxidation number and coordination number (6) Isomerism. Coordination isomers; linkage isomers. Structural isomers vs. stereoisomers (7) Geometric isomers (8) Continued (9) Optical isomers (10) Continued (11) Continued (12) Continued (13) Continued